Natural History and Genetic Studies of Usher Syndrome

National Eye Institute

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Abstract

The study involved a first visit with ocular exam and assessment of visual function, audiological and vestibular evaluation, and a blood sample for the purpose of molecular (DNA/genotyping) testing. The ocular examination included an assessment of: Best corrected visual acuity with manifest refraction A slit lamp examination and photography of lens opacity, if present Visual field examination (Goldmann visual field) Dilated ophthalmoscopic examination (2.5% phenylephrine and 1% tropicamide) Electroretinography (ERG) Fundus photography of retina, macula, and optic nerve Fluorescein angiography/ocular coherence tomography if macular edema is suspected. Auditory function were evaluated using the following battery of tests: Pure tone thresholds by air and bone conduction for 125-8000 Hz. Speech recognition threshold Word recognition ability Tympanometry Middle ear muscle reflex assessment Distortion product otoacoustic emissions (DPOAEs) Threshold equalizing noise test (TEN) Vestibular function were evaluated using the following procedures: A Videoonystagmography battery of tests including (a) oculomotor tests, (b) spontaneous, positional and positioning tests, and (c) caloric stimulation Rotary chair eye movements Vestibular evoked myogenic potentials (VEMP) Computerized dynamic platform posturography (CDPP) A total number of 249 participants were enrolled in this study with an accrual ceiling of 400 (200 affected participants and 200 unaffected participants). A total of 237 participants enrolled at NIH. A total of 12 participants have enrolled at the collaborative site, Queens College of the City University of New York (CUNY). Genotype-phenotype correlations have been performed for some of the genotypes. Computerized dynamic posturography, not previously performed on Usher patients, has provided new information about the vestibular function of both types of the syndrome and might be a useful tool in patient rehabilitation.